RSA Signature with Certificate's Private Key from PFX

Download Chilkat RSA ActiveX

Demonstrates how to use a certificate's private key from a PFX file to create an RSA signature.

Dim success As Long

'  Create an instance of a certificate store object, load a PFX file,
'  locate the certificate we need, and use it for signing.
'  (a PFX file may contain more than one certificate.)
Dim certStore As New ChilkatCertStore

'  The 1st argument is the filename, the 2nd arg is the
'  PFX file's password:
success = certStore.LoadPfxFile("chilkat.pfx","test")
If (success <> 1) Then
    MsgBox certStore.LastErrorText
    Exit Sub
End If

Dim cert As ChilkatCert
Set cert = certStore.FindCertBySubject("Chilkat Software, Inc.")
If (cert Is Nothing ) Then
    MsgBox certStore.LastErrorText
    Exit Sub
End If

Dim pkey As PrivateKey
Set pkey = cert.ExportPrivateKey()
If (pkey Is Nothing ) Then
    MsgBox cert.LastErrorText
    Exit Sub
End If

Dim pkeyXml As String
'  Get the private key in XML format:
pkeyXml = pkey.GetXml()

Dim rsa As New ChilkatRsa

'  Any string argument automatically begins the 30-day trial.

success = rsa.UnlockComponent("30-day trial")
If (success <> 1) Then
    MsgBox "RSA component unlock failed"
    Exit Sub
End If

'  Import the private key into the RSA component:
success = rsa.ImportPrivateKey(pkeyXml)
If (success <> 1) Then
    MsgBox rsa.LastErrorText
    Exit Sub
End If

'  This example will sign a string, and receive the signature
'  in a hex-encoded string.  Therefore, set the encoding mode
'  to "hex":
rsa.EncodingMode = "hex"

Dim strData As String
strData = "This is the string to be signed."

'  Sign the string using the sha-1 hash algorithm.
'  Other valid choices are "md2" and "md5".
Dim hexSig As String
hexSig = rsa.SignStringENC(strData,"sha-1")

Text1.Text = Text1.Text & hexSig & vbCrLf
Text1.Refresh

MsgBox "Success!"